This card trick demonstrated by Jason Suran is surprisingly simple to execute, and relies more on your audience's assumption that you're on the up-and-up than your ability to manipulate cards. Have your volunteer pick a card, and then find it with ease just by spelling out the name of the card. It's a cool effect that doesn't require any set up. The patter here is a little awkward, but you can adjust it to better fit your style. Just try to get a helper who's better at remembering what card they picked.